How does an electron in orbit not accelerate towards a proton in an atom?

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Discussion Overview

The discussion centers on the question of why an electron in an atom does not accelerate towards the proton in the nucleus, particularly in the context of classical mechanics versus quantum mechanics. Participants explore the implications of electric forces, orbital motion, and the nature of atomic structure.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question whether the electric force acting on the electron can be considered a centripetal force, suggesting that classical mechanics does not apply to atomic structures in the same way it does to larger celestial bodies.
  • One participant emphasizes that quantum mechanics is necessary to explain the behavior of electrons in atoms, noting that electrons do not orbit the nucleus in a classical sense.
  • Another participant draws a comparison between the electron-proton interaction and the Earth-Moon system, questioning why the Moon does not collapse into the Earth despite gravitational attraction.
  • It is proposed that the Moon's orbit involves a balance of falling towards and moving away from the Earth, and that if the forces were electromagnetic rather than gravitational, the dynamics would be drastically different.
  • One participant explains that the electron exists in a probabilistic distribution around the nucleus, influenced by the uncertainty principle, which prevents it from being in a defined orbit.
  • There is a mention of the energy required to combine an electron and a proton, suggesting that electromagnetic forces alone are insufficient for such a merger without significant external energy, as seen in supernova events.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of classical mechanics to atomic systems, with some arguing against it while others draw parallels with celestial mechanics. The discussion remains unresolved regarding the exact nature of electron behavior in atoms and the forces at play.

Contextual Notes

Limitations include the reliance on classical analogies that may not accurately represent quantum phenomena, as well as the complexity of the forces involved in atomic interactions that are not fully resolved in the discussion.

kshah93
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If the proton in the nucleus of, say a hydrogen atom, exerts an attractive force on an electron that is in orbit, why doesn't the electron move towards the proton? And does this have anything to do with the electric force being the centripetal force?
 
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kshah93 said:
does this have anything to do with the electric force being the centripetal force?

no, it doesn't. that is, you cannot apply the classical mechanics of gravitating bodies to an electron and the nucleus it "orbits"...and i use quotations b/c en electron does not orbit the nucleus of an atom in the traditional sense of a planet orbiting a star for instance. quantum mechanics are required to explain why an electron doesn't plunge radially into the nucleus of an atom, and i do not pretend to know the details myself...i have a very basic understanding of it, and as such could not begin to explain it beyond what I've already said. with that, i did notice another recent thread started by someone who wanted to share what he felt was a very good short video on quantum physics. whether that's true or not, i don't know, but the first few minutes of the video explain (or perhaps under-explains) in layman's terms why an electron does not spiral into the nucleus of an atom via a traditional orbit. here's the thread:

https://www.physicsforums.com/showthread.php?p=3240077#post3240077"
 
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94JZA80 said:
no, it doesn't. that is, you cannot apply the classical mechanics of gravitating bodies to an electron and the nucleus it "orbits"...
QUOTE]

..but classical mechanics can be apllied to earth-monn system, right. Then why doesn't moon collapse on the Earth despite the fact that it is constantly pull by eart diue to its magnetic pull.
 
ank160 said:
94JZA80 said:
no, it doesn't. that is, you cannot apply the classical mechanics of gravitating bodies to an electron and the nucleus it "orbits"...
QUOTE]

..but classical mechanics can be apllied to earth-monn system, right. Then why doesn't moon collapse on the Earth despite the fact that it is constantly pull by eart diue to its magnetic pull.

It's vectors.

The moon is actually moving away from the Earth extremely slowly.

An orbit is actually falling toward and away from an object at the same rate. If you are moving away a tiny bit faster then falling toward, you will one day escape, if you move toward a tiny bit faster then away, you will eventually connect.

BTW it has nothing to do with magnetic pull when it comes to the earth-moon orbit, its gravity.

If for example the Earth was positive, and the moon negative in any meaningful way, the two object would collide faster then you can imagine due to electro-magnetism's incredibly stronger nature compared to gravity.

As I understand it, the reason the electron and proton don't combine is quantum related in this way, first the electron is not really in orbit around the proton of an hydrogen atom, or any other atom like we envision the moon around the earth. The electron, or electrons are in a shell of probalistic distribution around the nucleus. Since the uncertainty principle dictates that we can not know both the location and speed of a particle, this is why the electron can never be verifiably positioned around the nucleus.

So, the whole "lose energy and fall upon the proton" isn't as straightforward as that, secondly, the mass of the proton and the electron are less then the neutron. This has for consequence that you would need to supply energy to make both of them collapse together. The electromagnetic force isn't sufficient for that to happen. So an electron that is in an orbital cloud above a nucleus, can not just lose energy and merge with the proton.

The best known method of combining proton and electron is the massive energy of a super-nova that collapses the iron core of a super giant star into a super dense neutron star. When the star goes super-nova, the energy liberated is stupenduous, thus enabling the combination of proton and electron, thus forming a neutron star.

I hope I managed to answer, within my limited ability, your question.
 

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